p. 213-255 | Food security and water security in the Mediterranean are intrinsically linked and are facing similar challenges. Food security is threatened mainly by the high dependency of Mediterranean countries on food imports, making them vulnerable to external pressures such as volatile food prices. From a nutritional standpoint, the number of overweight and obese people has increased as a result of the traditional Mediterranean diet being abandoned. Water security has degenerated due to the deterioration of internal freshwater resources, both in terms of water quantity and quality, with a high dependency on external water resources, higher regional water footprints than the global average, increasing scarcity of renewable water resources, an increased number and capacity of dams exerting pressure on freshwater ecosystems, and a growing risk of conflicts between water users and countries. Access to water and sanitation remains a major challenge in the region. Territorial divisions separating coastal urban and remote rural areas are growing stronger, making isolated populations such as smallholder farmers particularly at risk of food and water insecurity. With climate change, precipitation is expected to decrease and temperatures to rise in the region, which will affect water supply (and thereby energy and food supply). It will also directly affect soil moisture and crop growth, thereby further increasing irrigation water needs. There are clear but difficult to measure interactions between the water, energy and agricultural sectors, as they are all interdependent, which calls for integrated policies and management. Agriculture being the largest water user in the region, further efforts need to be made to promote the use of non-conventional water resources. The conservation and restoration of Mediterranean agroecosystems is key to ensuring sustainable development. This requires better management of continuing arable land loss, land use intensification, and soil erosion and salinization. Integrated Water Resources Management and Water Demand Management (WDM) provide guidelines for achieving better water efficiency and reducing conflicts between users.

Seventy-one percent of the earth surfaces is covered by oceans. Water therefore is an important habitat for microorganisms and the other living beings. A consistent microbial biodiversity is present in water from phototrophs to chemioorganotrophs. The complex relationships between different microorganisms and the environment are often modified by organic, chemical and physic contaminations. The input of organic material can determine pathogenic pollution. The presence of pathogens has to be monitored to eliminate serious problems for animal and human health. Water, in fact, can be a vehicle direct (drinking water) or indirect (irrigation water) for microbial pathogens | Il 71% della superficie terrestre è costituito dagli oceani. L'acqua pertanto è un importante ambiente per i microrganismi, oltre che per tutti gli altri esseri viventi. Una grande varietà di tipi microbici colonizzano l'habitat acquatico, dai fototrofi ai chemiorganotrofi. Le dinamiche che si creano fra i diversi componenti microbici e l'ambiente sono spesso alterate da contaminazioni organiche, chimiche e fisiche. L'immissione di materiale organico può anche essere fonte di inquinamento di microrganismi patogeni la cui presenza va monitorata al fine di evitare seri problemi alla salute umana e animale. L'acqua, infatti, può rappresentare un veicolo di trasferimento, sia diretto (acqua potabile), sia indiretto (acque di irrigazione), di microrganismi patogeni

In irrigated as well as in rainfed areas, it is essential to work on the increase in water/ moisture-use efficiency of the crops. Since water is precious, suitable methods of irrigation and in-situ moisture conservation practices are to be adopted by the farmers on the basis of the suggestions made by the agricultural scientists of the country. In rainfed areas, suitable tillage can play a significant role in the conservation of moisture. Selection of crops and their varieties, fertilizer management and proper methods of sowing are the factors for increasing the moisture-use-efficiency and productivity. Methods of irrigations are to be modified in irrigated areas mainly to check the unnecessary loss of water.

Latent heat of evaporation represents a large outgoing component of the energy balance established at a crop-stand surface. This explains why agriculture uses approximately 70% of all the freshwater withdrawn in the world. Increasing demand for water due to population growth, competition with industrial, domestic and environmental requirements, and the decreasing quality of water, limit the agricultural capacity for food production. The Water Resources, Development and Management Service (AGLW) of the Food and Agricultural Organization of the United Nations (FAO) is carrying out activities aimed at helping country members in supporting sustainable water management to securing food for a growing population. These activities cut across the various levels of the water domain, going from the (inter)national policy level down to local-level field applications. In this article, FAO's experiences in agricultural water management are used to provide lessons from the past and indicate directions for future challenges. (Résumé d'auteur)